<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<script type="text/javascript">
			
			var a = {
				i: 1,
				toString:function() {
					return a.i++;
				}
			}
			
			console.log(a == 1 && a == 2 && a == 3)
			
			
			var b = [1,2,3]
			b.join = b.shift;
			console.log(b == 1 && b == 2 && b == 3)
			
		</script>
	</body>
</html>
